The suburban area of Ulaanbaatar, the capital city of Mongolia, has an extensive “Ger area” where residents live in Ger or Bai-shin. Recently, Ger areas have reportedly expanded in accordance with the increasing population. Previous studies of Ger areas have tended to focus on the “unique sight” of Gers in the city and few have discussed the residents’ point of view. For this study, the two analyses focus on and clarify the changes in Ger areas over time, using aerial photographs, first to clarify Ger areas’ expansion, the regions that corresponded either to “Ger areas,” consisting of continuous Kha-shaas, or “Apartment areas,” consisting of apartments or modern buildings, which were marked by lines. The second is to clarify the internal changes in Kha-shaas, and identify individual Kha-shaa, Ger and Bai-shin within each Kha-shaa marked at three selected sites. In addition, Kha-shaa were counted and categorized according to whether they contained “Ger only”, “Ger and Bai-shin”, or “Bai-shin only.” Through these analyses the clarified Ger areas were understood to be redeveloped for apartments in the socialist era but after democratization the promised development did not take place. Old Kha-shaa consisted of “Bai-shin only” or “Ger and Bai-shin”, and new Kha-shaa consisted of “Ger only”. In other words, Ger have been gradually decreasing because of the building of Bai-shin, which are more comfortable and convenient for urban living. Although progressively more Bai-shin are being built over time, Ger do not disappear because they are being used for different purposes by residents. Those who relocate to Ulaanbaatar rely on family members who live in Ger areas for temporary accommodation in their Ger. “Gers in the city” not only means a unique sight but also living in a Ger is very rational in urban life.